[2000CAYukon]

Does the EGR solenoid hold vacuum on the TBI side? For a quick test, remove the vacuum line from the TBI to EGR solenoid and plug it. If the problem clears up, the solenoid or EGR valve is your problem.

My problem is similiar except (in my case) that the timing is jumping around at idle. Double check that your timing is 0 with est disconnected.

//2000CAYukon